Note 5 - Intangible Assets (Tables)
 12 Months Ended
Mar. 31, 2022
Notes Tables  
Schedule of Finite-Lived Intangible Assets [Table Text Block]
   

March 31, 2022

    

March 31, 2021

  
   

Cost

    

Weighted

Average

Amortization

Period

(Years)

    

Accumulated Amortization

    

Net

Carrying

Amount

    

Cost

    

Weighted

Average Amortization Period

(Years)

    

Accumulated Amortization

    

Net

Carrying

Amount

  

Patents & Trademarks

   $ 35,794       10 - 15     $ (19,751 )   $ 16,043     $ 35,794       10 - 15     $ (16,871 )   $ 18,923  
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

For the fiscal years ended March 31,

        

2023

   $ 2,882  

2024

     2,882  

2025

     2,465  

2026

     2,529  

2027

     1,486  

Thereafter

     3,799  
    $ 16,043